We get so many of these and always the op is convinced that its the alarm, I remember as an engineer telling a customer over the phone it was a low battery on their smoke, they insisted I come out. £70.00 plus VAT (it was the early 90's) callout later, I found an old smoke detector in a kitchen drawer with the battery still in it.
Its like we tell them what it is and the dont believe us
Had exactly the same thing many times.
Once a customer was convinced it’s was the alarm and insisted we attend site to fix. I advised that we would charge for the visit.
On arrival I found an old carbon monoxide detector down the back of a sideboard in the lounge, I was on site less than a minute.
they kicked off big time when they got the bill and canceled there contract, they did pay though.
good riddance nob heads.
I'd suggest you power it all down then find out it's a battery operated bit of junk, nest smoke, other smoke detector then I'd look for alarm clocks birthday cards etc. A powered down alarm is just that.
If I was a betting man-
I'd wager you've more chance of getting a hand job off her majesty the queen than your powered down alarm making the "chirp"
You've probably got a brand new in box, carbon monoxide or smoke alarm in the cupboard....